diff --git a/apex/apex.go b/apex/apex.go
index 1f06187..6ef8a87 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -178,6 +178,10 @@
 	// used in tests.
 	Test_only_force_compression *bool
 
+	// Put extra tags (signer=<value>) to apexkeys.txt, so that release tools can sign this apex
+	// with the tool to sign payload contents.
+	Custom_sign_tool *string
+
 	// Canonical name of this APEX bundle. Used to determine the path to the
 	// activated APEX on device (i.e. /apex/<apexVariationName>), and used for the
 	// apex mutator variations. For override_apex modules, this is the name of the
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 78a6bb8..8aaa31a 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -7683,6 +7683,28 @@
 			name: "myapex",
 			key: "myapex.key",
 			updatable: false,
+			custom_sign_tool: "sign_myapex",
+		}
+
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+	`)
+
+	apexKeysText := ctx.SingletonForTests("apex_keys_text")
+	content := apexKeysText.MaybeDescription("apexkeys.txt").BuildParams.Args["content"]
+	ensureContains(t, content, `name="myapex.apex" public_key="vendor/foo/devkeys/testkey.avbpubkey" private_key="vendor/foo/devkeys/testkey.pem" container_certificate="vendor/foo/devkeys/test.x509.pem" container_private_key="vendor/foo/devkeys/test.pk8" partition="system_ext" sign_tool="sign_myapex"`)
+}
+
+func TestApexKeysTxtOverrides(t *testing.T) {
+	ctx := testApex(t, `
+		apex {
+			name: "myapex",
+			key: "myapex.key",
+			updatable: false,
+			custom_sign_tool: "sign_myapex",
 		}
 
 		apex_key {
diff --git a/apex/key.go b/apex/key.go
index e2695d7..259060f 100644
--- a/apex/key.go
+++ b/apex/key.go
@@ -123,13 +123,18 @@
 		containerCertificate string
 		containerPrivateKey  string
 		partition            string
+		signTool             string
 	}
 	toString := func(e apexKeyEntry) string {
-		format := "name=%q public_key=%q private_key=%q container_certificate=%q container_private_key=%q partition=%q\n"
+		signTool := ""
+		if e.signTool != "" {
+			signTool = fmt.Sprintf(" sign_tool=%q", e.signTool)
+		}
+		format := "name=%q public_key=%q private_key=%q container_certificate=%q container_private_key=%q partition=%q%s\n"
 		if e.presigned {
-			return fmt.Sprintf(format, e.name, "PRESIGNED", "PRESIGNED", "PRESIGNED", "PRESIGNED", e.partition)
+			return fmt.Sprintf(format, e.name, "PRESIGNED", "PRESIGNED", "PRESIGNED", "PRESIGNED", e.partition, signTool)
 		} else {
-			return fmt.Sprintf(format, e.name, e.publicKey, e.privateKey, e.containerCertificate, e.containerPrivateKey, e.partition)
+			return fmt.Sprintf(format, e.name, e.publicKey, e.privateKey, e.containerCertificate, e.containerPrivateKey, e.partition, signTool)
 		}
 	}
 
@@ -145,6 +150,7 @@
 				containerCertificate: pem.String(),
 				containerPrivateKey:  key.String(),
 				partition:            m.PartitionTag(ctx.DeviceConfig()),
+				signTool:             proptools.String(m.properties.Custom_sign_tool),
 			}
 		}
 	})